Why Your New Year’s Diet Will Fail

It may be the most ubiquitous resolution of them all, but losing weight for good is a losing battle for almost all of us—and it’s not even a surefire way to get healthy.

12.30.14 5:45 AM ET

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Not long after the holiday presents are put away and the guests have gone home, another season begins. Instead of lights and gifts, this one is filled with broken promises and guilt. As one year slides inexorably into the next, many of us—around 45 percent, according to various surveys—make New Year’s resolutions, most commonly to lose weight. And it’s not hard to understand why: The Centers for Disease Control and Prevention and the World Health Organization consider obesity a looming global crisis, and it seems that every day we read more stories about how our expanding waistlines are slowly strangling our well-being.

The problem, says UC Davis physiologist and nutritionist Linda Bacon, is that very few people can lose weight and keep it off. Diets not only fail to make us thinner, they also fail to make us healthier in the long term. The average dieter will lose 10 pounds or so, then slowly gain it back, plus an additional five pounds for good measure, much of it fat, and a slower metabolism and increased risk of cardiovascular disease. To Bacon and a growing number of other experts, then, one of the best ways to improve health is by starting to separate it from weight.

“We have this idea that losing weight is as simple as burning more calories than you consume and that weight is under the control of the individual. But when you look at the science, you find that it’s not true,” Bacon says. “However, you can make positive changes and trust your body to see what happens and trust that it will bring you to health even without weight loss.”

Dieting isn’t new. While juice cleanses and weight loss colonics seem like relatively recent inventions, they have a long history. In the early 1800s, the English poet Lord Byron’s diet of apple cider vinegar and water became a popular choice for those looking to lose weight. In 1863, London undertaker and coffin maker William Banting published “Letter on Corpulence, Addressed to the Public,” which detailed his weight loss following a low carbohydrate diet. The pamphlet was so popular and influential that “banting” temporarily became a synonym for dieting, and his treatise has remained in print to this day.

Other popular early diets involved smoking when you were hungry instead of eating (a diet created and promoted by the cigarette industry), eating grapefruit with every meal, chewing each bite of food hundreds of times, and the tapeworm diet, which involved swallowing a pill filled with (you guessed it) tapeworms. There was also the grapefruit diet, the cabbage soup diet, and the cookie diet. Then the commercial weight loss behemoths Weight Watchers and Jenny Craig joined this crowded field.

But did these diets work? At first, the results looked promising. People did generally lose weight on these diets. As scientists followed these same people over time, however, a clear trend emerged. The weight people lost tended to return. Yo-yo dieting, also known as weight cycling, is also believed to slow the body’s metabolism permanently, making it easier to gain weight and harder to lose it. It also can increase risks for cardiovascular disease. So while weight loss diets might temporarily make people thinner, they typically doesn’t make them healthier in the long run.

What’s more, very low calorie diets tended to reduce muscle mass rather than the body’s fat stores. The regained weight, however, was overwhelmingly fat. A team of Swiss scientists at the University of Fribourg have studied this phenomenon of fat overshooting for nearly two decades and found that people tend to overeat after they stop dieting, and that the overeating continues until the person’s fat mass is well above their pre-diet starting point. The researchers have documented this phenomenon in those with obesity, but fat overshooting is much more likely in individuals with weights in the normal range.

Evelyn Tribole, a clinical nutritionist in Southern California, frequently cites the Swiss research to her patients, especially those looking for help in losing weight.

“I tell them that dieting is not really going to help them lose weight. They really freak out at the idea of ‘fat overshooting,’ and it helps us develop more realistic goals,” Tribole says.

That diets don’t work is common enough knowledge. It’s even appeared in commercials for Slim Fast and Special K, both of which are, well, diet products. Yet we keep doing the cleanses, buying the meal replacement bars, and joining Weight Watchers.

“It’s pretty much the best business model you can come up with. It’s the only thing we buy that, when the product fails, we all blame ourselves and then go buy another version,” Tribole said.

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“Scratch the surface of most of the gluten-free literature, or of similar things, and you’ll find a desire to lose weight,” Brown says.

It’s no wonder, she adds. With fears about obesity ever present, as well as the West’s intense societal stigma against fat, it makes sense to want to lose weight. What people need to stop and ask, however, is whether it’s realistic to diet and lose weight long term, and whether that will improve health. The answer to both questions, Brown says, is no.

“If you look at the studies, most of them stop after six months, one year, two years,” Brown says. She wanted to know what happened over five years, or even 10, but the scientific literature had little to offer.

The longest study Brown dug up was the Look Ahead Study, which randomized 5,145 adults with diabetes to either an “intensive lifestyle intervention focusing on weight loss” or a control group and then followed them for 13.5 years. After 9.5 years, however, the study was halted. Although the intervention group did lose more weight than the control group (6.0 percent versus 3.5 percent of starting body weight), the researchers found no significant difference in cardiovascular events like heart attack and angina, or in premature death.

Nor do these studies address the structural and systematic issues that contribute to obesity, such as poverty and stress.

“Most of the diseases we blame on nutrition are actually diseases of disempowerment,” Bacon said.

Both Bacon and Tribole emphasize that just because weight loss diets don’t work—whether you call them a diet, a lifestyle change, or “healthy eating”—doesn’t mean people can’t focus on making meaningful changes in their health, eating, and exercise habits, even if it doesn’t change the number on the scale. Fitness is possible at any size, and physical activity is one of the best things people can do for their health at any weight—fat, thin, or in between. And it doesn’t have to change their weight to have significant benefits. A 2013 study in the Journal of Health Psychology found that exercise improves body satisfaction, and Brown points out that we tend to take better care of things we like than things we hate.

Instead of just cutting out whole food groups, Bacon says people should pay attention to how food makes them feel.

“If someone is on an all junk food diet, chances are they aren’t feeling good in their body. They’re probably constipated most of the time,” she says.

And if people find themselves dissatisfied with how often they turn to fast food, Bacon says to try things like batch cooking. Don’t feel confident in the kitchen? Take a cooking class. Learn how to cook food you actually like.

“Food is more than calories and nutrients. We need to be satisfied by the food that we’re eating,” Bacon says.

Tribole tells her patients not to change what they eat but how.

“Eat without distraction for just one meal a day. Turn off the TV, put down your phone, and log off the computer. Pay attention to what you’re eating, the texture, how it tastes, how you feel while eating, and your hunger and fullness cues,” she says.

Brown says she would also like to see people, especially women, drop the fat talk, that constant criticism of every single body part.

“It really just makes us feel awful,” she says.

These efforts might not change how much people weigh, but that’s not the point. They just might change how they feel, how healthy they are, and how they live their lives.